Manufacture of zinc salts of high molecular weight alkylated hydroxy aromatic compounds



v July 21, 1953 J w. HUTcHEsoN ET AL 2,646,402

MANUFACTUR OF ZINC SALTS OF' HIGH MOLECULAR WEIGHT ALKYLATED HYDROXYAROMATIC COMPOUNDS Filed Feb. ll, 1950 Patented July 21, 1953 2,646,402ICE MANUFACTURE F ZINC SALTS 0F HIGH MOLECULAR WEIGHT ALKYLATED HY-DROXY AROMATIC COMPOUNDS Jolln W. Hutcheson, Beacon, and Edwin C'.

Knowles, Glenham, N. Y., assignors to The Texas Company, New York, N.Y., a corporation UNITED STATE-iis PATENT oF of Delaware 4 Claims.

This invention relates to lthe manufacture of zinc salts of highmolecular weight alkylated hyp droxy aromatic compounds, such as alkylphenols,

wherein the substituent alkyl group on each ben- .,zene nucleus containsfrom k to 30 carbon atoms.

The zinc salts of alkylated hydroxy aromatic compounds, such as alkylphenols, having one or more high molecular weight alkyl side chainssubstituted on the ring, are valuable additives for vmineral lubricatingoil. VThe zinc alkyl phenolate Yof the present invention is particularlyuseful, vwhen used in conjunction with a magnesium alkyl phenolate, asan additive for an airplane engine oil of the highly refined residualtype, as disclosed and claimed in the copending application of FredericC. McCoy, Bill L. Benge, Edwin yC. Knowles, and Charles C. Towne, SerialNo.

, 286,634 iiled May 7, 1952-as a continuation-in part of Serial No.143,836,7February 11, 1950, now

abandoned.

, It is known to prepare polyvalent metal salts of lower molecularweight alkyl phenols or other alkylated hydroxy aromatic hydrocarbons bya l double decomposition procedure, involving first I forming the alkalimetal salt of the alkyl phenol, followed by a reaction with a solublepolyvalent metal salt, such as a chloride. It has been found that theconventional procedure of carrying out this double decompositionreaction is unsatisfactory in the preparation of the zinc salts of highmolecular weight alkylated hydroxy aro- ,matic hydrocarbons, such asalkyl phenols,

I wherein the substituent alkyl group of the benzene nucleus containsfrom 15 to 30 carbon atoms, since the quality of the iinal productisunsatisfactory with respect to solubility and effectiveness as aresidual mineral lubricating oil additive. It is accordingly a principalobject of the present invention` to provide an improved process ofsynthesizing the zinc salts of higher molecular weight alkylated hydroxyaromatic hydrocarbons, such as alkyl phenols, wherein the substituentalkyl group of the benzene nucleus contains from 15 to 30 carbon atoms,in order to provide products of the required solubility and quality to Iserve as lubricating oil additives, particularly'y of "ferre'd materialfrom the standpoint of additive 2 manufacture is an alkyl lphenolprepared by alkylating a mononuclear monohydroxy aromatic hydrocarbon,such as phenol, cresol or other alkyl phenol, with an olefin polymer,such as a propylene polymer, containing from about 16 to 30 carbonatoms. vAlso hydrogenated cardanol produci-ng a C15 alkyl phenol is asatisfactory starting material. Likewise, alkylated mononuclearpolyhydroxy aromatic hydrocarbons, such as hydroquinone, pyrogallol Vandother dihydric and trihydric phenols, can be employed. Also, alkylatedpolynuclear hydroxy aromatic hydrocarbons, such as the naphthols, can beused. From the standpoints'of availability and economy, alkyl phenolprepared by alkylating phenol with a C18-Cso, and preferably C18-C26,propylene polymer in the presence of anhydrous I-IF catalyst asdisclosed and claimed in the copending application of YLouis B. BosSerial No. 143,784 led of even date herewith, or in the presence ofAlCh-HSOq. complex catalyst as disclosed and claimed in the copendingapplication of Fred W. Moore and Herman D. Kluge Serial No. 143,782,

' led of even date herewith, is preferred. VFor the purpose of ease indescription, a C15-Cso alkyl phenol of the foregoingtype will bereferred to in the following text; but it is to be understood that thisis solely by way of example, 'and that the description applies to theother alkylated hydroxy aromatic hydrocarbons specified.

The synthesis of the zinc salt of a C15-Cso alkyl phenol in accordancewith the present invention involves an improvement on the known doubledecomposition reaction procedure, wherein the alkyl phenol is reactedwith an alkali metal alcoholate, generally sodium butylate, and theresulting sodium alkyl phenolate is reacted with a soluble zinc salt,such as the acetate, to form the zinc alkyl phenolate. The doubledecompotition reaction between the sodium alkyl phenolate and zincacetate is represented by the following equation: d

The improvement features of the present invention involve the following.Anhydrous conditions are maintained throughoutv the reaction andrecovery of the product. Substantially equal molar amounts of the alkylphenol and the alkali metal butylate or other alcoholate, in solution inan excess of the corresponding anhydrous aliphatic alcohol, are reactedwith the soluble zinc salt at an elevated temperature providing alcoholrefluxing conditions for a reaction time in excess of hours and up to 48hours, preferably about 24 hours, In this reaction, the sodium butylateor other alcoholate in solution in a portion of the total anhydrousaliphatic alcohol is added slowly or dropwise to a premixture of thealkyl phenol and the zinc salt in the balance of the anhydrous alcoholat a lower temperature of the order of -'70 1C., preferably about C.;and then the temperature of Ythe resulting mix is raised to the alcoholreiluxing temperature and maintained -a-t this temperature for thestated long reaction time. A slight excess over the stoichiometricequivalent of 1/2 molar amount based on the other reactants of the zincsalt is employed in the reaction. A min.- eral lubricating oil, whichforms a concentrate of the nal zinc alkyl phenolate in the oil, is addedonly after completion of the reaction and filtration of the reaction mixto remove the precipitated alkali metal salt. A light hydrocarbonsolvent, such as pentane, is added to the mineral lubricating oilconcentrate of the zinc alkyl phenolate, and the resulting mix reltered,followed by stripping of the hydrocarbon solvent, to obtain a purifiedconcentrate as the desired nal product. The foregoing features have beenfound critical in producing a zinc alkyl phenolate of the requiredsolubility and quality for use as an additive in residual minerallubricating oil of the airplane engine oil type.

Referring to the drawing, the essential starting materials areillustrated for the preferred example as sodium metal, anhydrous butylalcohol, a C15-Cso alkyl phenol and zinc acetate. In place of anhydrousbutyl alcohol, other anhydrous alphatic alcohols boiling above theboiling point of water, selected from the group of C4 to C6 aliphaticalcohols can be employed. In place of the zinc acetate, other Zinccarboxylate or inorganic salts, the acidic portion of which forms analkali metal salt'which is insoluble in the anhydrous aliphatic alcohol,such as the formate, butyrate, chloride, etc., can be used. Also, otheralkali metals, such as potassium, can be employed. It will be understoodthat the reactants illustrated are preferred.

An important feature of the present invention is the provision ofsubstantially anhydrous reactants and the maintenance of anhydrousconditions throughout Vthe synthesis. For this purpose, the sodium metalis maintained submerged in a suitable liquid, such as toluene, which isinert to the metal; and the metal is out or subdi-vided in small piecesfor the reaction while y submerged in the liquid. rIhe butyl alcohol isdried by distillation before being used; and the zinc salt is carefullyheated to fusion to be sure that it is anhydrous. In the case of zincchloride, this can also be dried by reuxing in the presence of toluene.The alkyl phenol and the zinc acetate or other zinc salt are charged inthe ratio of one molar quantity of the alkyl phenol to slightly morethan 1/2 molar quantity of the zinc salt, together with a portion of theanhydrous butyl alcohol7 to a stirred reactor fitted with a condenserfor refluxing, and provided with drying tubes on all openings to theatmosphere. In a separate vessel, the freshly cut sodium metal, whichhas been protected from the atmosphere by submergence as previouslydescribed, is mixed with the balance of the anhydrous butyl alcohol toform a sodium butylate solution in excess anhydrous butyl alcohol.

The sodium butylate (Reactant No. l) in the Vmixture of the alkyl phenol(Reactant No. 2) and the zinc acetate (Reactant No. 3) in solution inthe balance of the alcohol at a temperature of about 30-70o C.,preferably about 50 C., while the contents of the reactor are stirred.This has been found important in producing precipitated sodium acetatecrystals of larger size which can be properly filtered from the reactionmix. Moreover, all openings from the reactor to the atmosphere arefitted with drying tubes to protect the reactants from atmosphericmoisture and maintain the anhydrous conditions. Following the additionof the sodium butylate solution, the reactor is then heated to a butyllalcohol Areflux temperature and main-tained at that temperature withcontinued stirring for a reaction period in excess of 20 hours,preferably about 24 hours. This long reaction period has been foundimportant in producing Va zinc alkyl phenolate of the desired qualityfor purposes of the present invention.

The resulting reaction mix while hot is then filtered, preferablythrough a layer of dried solid filter-aid material such as Super CelI-Iy-Flo, to remove the precipitated sodium acetate. The resultingfiltrate of Zinc alkyl phenolate in solution in anhydrous butyl alcoholis then mixed with sumcient dry mineral lubricating oil, such as arefined paraffin base distillate motor oil of about SAE l0 grade, or alrefined naphthene base oil hav-ing an SUS viscosity at F. of about 300,to produce an ultimate concentrate of the zinc alkyl phenolate in thelubricating oil of about l0-60%, preferably about 50%. The butyl alcoholis then stripped from the lubricating oil concentrate by distillationwith the aid of a dry gas, such as dry air.

In order to effect further purification of the concentrate and improvethe quality -of the zinc alkyl phenolate product as a lubricating oiladditive, the concentrate is then mixed with a light hydrocarbon solventwhich is also anhydrous, such as dry pentane, hexane or light gasoline.A volume of the light hydrocarbon solvent equivalent to about 1/2 totwice the volume of the concentrate, preferably about an equal volume,is employed for this purpose. As shown, dry pentane is preferred as thehydrocarbon solvent. The resulting solution is then reltered while hotin the manner described above for the first filtration. The pentane orother hydrocarbon solvent is then stripped by distillation with the aidof dry air to obtain the purified concentrate of zinc alkyl phenolate asthe nal product.

The following examples are given to further illustrate the presentinvention:

EXAMPLE '1 v12,84 grams of alkyl phenol (3 mols), wherein thesubstituent alkyl group on the benzene nucleus contained an average of24 carbon atoms, together with 300 grams of fused C. P. Zinc acetate(1.5 mols-i-25 grams, were mixed with 305 grams of a naphthene basedistillate lubricating oil having an SUS viscosity at 100 F. of 315, andabout half of 2,000 grams of anhydrous kbutyl alcohol. The mixture wascharged to a flask tted with a stirrer and condenser and heated to F. Ina separate flask, 69 grams (3 mols) of sodium metal were reacted withthe balance of the butyl alcohol. The resulting sodium butylate solutionin excess butyl alcohol was then added to the other reactants, and thematerials heated then stripped, and the lubricating Yoil concentratereltered. Considerable foaming was experienced during the reuxing whichrequired the use of an anti-foam agent to control, and difficulty wasexperienced in the ltrations. A yield of 2,070 grams of a lubricatingoil concentrate of zinc alkyl phenolate was secured, which analyzed toan ash content of 4.68% basis a theoretical ash content of 4.4%, and azinc content of 3.67% basis a theoretrical zinc content of 3.56%. Thematerial'was soluble in a distillate paraffin base motor oil ofr SAEgrade to the extent of dissolving 1% of the Zinc alkyl phenolatetherein, and the resulting solution remained clear on storage at atemperature of 120 F.

` A second batch of zinc alkyl phenolate concentrate, employing the samequantities of .materials and the same procedure as above set forthexcept that a reaction time` under reiiuxing conditions of hours wasused, yielded 1950 grams of a concentrate which also analyzed somewhathigh in ash and zinc contents based on theoretical. These two batches ofconcentrate were combined for engine testing. `While the productsappeared satisfactory on the basis of their ash and zinc'contentsV andsolubility in distillate lubricatingY oil, the results of the enginetest were not satisfactory as described in greater detail hereinbelow.

EXAMPLE 2 In this case zine chloride was employed as the zinc salt, thematerials employed being as follows: Y Y Y 40 grams (175i mol+ 6 grams)500 mls. Naphthene base distillate lubricating oil 224 gramsV The 'sameprocedure was vemployed as in the foregoing Example l except that theZinc chloride was added to the alkyl phenol, the naphthene baseVlubricating oil and part ofthe butyl alcohol at a temperature of 70 C.,and this temperature maintained for ll/ hours prior to the additionofthe sodium butylateV solution in the remaining butyl alcohol.Following the lrapid addition of the sodium butylate solution, thereactants were heated at butyl alcohol reflux for 20 hours. A yield of405 grams of concentrate which analyzed to an ash content Vof 4.37%basis a theoretical 4.54%, and a Zinc content of 3.50% basisatheoretical 3.63%, was obtained. The material was soluble vin a refinedvresidual lubrieating oil of the airplane engineA oil type to the extentof dissolving 1% of the zinc alkyl phenolate in the oil, the solutionremaining clear for ve months storage at 120 F. While the productappeared satisfactory basisrthe ash and zl'inc contents as well asitssolubility and storage properties, the results of engine testing showedthe product to be unsatisfactory from the standpoint of maintainingdesired engine cleanliness as discussed hereinbelow. The residuallubricating oil oiv the airplane engine oil typewasAv` refined bysolvent disasphalting, solvent renn-r ing, solvent dewaxing, claycontacting and clay -ltering Airplane engine oils of this type generallyhave an SUSviscosity at 210 F. at about 804130. The particular oilselected for the above 210 F. of about 120.

described storage test had an SUS viscosity atl at 120 F. and at roomtemperature.

, EXAMPLE 3 y The materials employed wer'i C a1ky1pheno1 38s am 1 moiSgldium metal 23 gms (g. m0l)) Zmc acetate CP fus gram (1/2 mol 8grams)- Butyl alcohol 800 mls. Naphthene base distillate lubricating oil419 grams The procedure employed was similar to Example 1 above, exceptthat the sodium butylate solution wasadded dropwise to theotherreactants at a temperature of `50 C., and then the temperature ofthe resulting mix was increased gradually to butyl alcohol reux andmaintained at a reflux'temperature for 20 hours. A yield of 633 grams ofa concentrate analyzing to an ash content of 3.57% basis a theoreticalof 4.82%

and a zinc content of 2.19% basis a theoretical of 3.87%, was obtained.The material was soluble in the residual airplane engine oil of grade tothe extent of 1% of the pure zinc alkyl phenolate when initiallyprepared, but a slight precipitate developed in one month storage bothWhile the material did not appear particularly promising Afrom thestandpoints of low ash and zinc contents and poor stability on storage,it was nevertheless engine tested; but the engine test results were notVsatisfactory as set forth hereinbelow. l

EXAMPLE 4 The same procedure as in Example 3 was employed except that a10% excess` quantity of alkyl phenol Was present'in the reacting mix.Quantities of materials employed were as follows:-

Cm alkyl phenol 915 grams (2 mols+83 grams) aaa-- 2 sa 1 mc a e a e userams mo s Butyl alcohol 1500lnls. 7 gram Naphthene base distillate vlubricatmg oil 875 grams A yield was obtained of 1604 grams ofconcentrate analyzing 4.86% ash based on a. theoretical of 4.52% and3.03% zinc based on a theoretical of 3.50. The material was soluble inthe residual airplane engine oil of 120 grade to the extent ofdissolving 1% of the Zinc alkyl phenolate therein when freshly prepared;but a precipitate formed on storage at both 120F. and room temperaturein one month. The product was engine tested, butA the results were. notsatisfactory pointed out hereinbelow.

EXAIWPLE 5k The materials employed were: C23 alkyl phenol 1688 grams (4mols) Sodium metal 92 grams (4 mols) Y Zinc acetate CP yfused 400 grams(2 mols 32 grams) Butyl alcohol (dry) 3000 mls. Naphthene basedistillate 1ubr1cating'o1l Suglcient to make 50% concenrate In thispreparationfprecautions were taken to maintain absolutely anhydrousconditions. The butyl alcohol was dried by distillation before use. Thesodium metal was maintained and cut under toluene. The naphthene baselubricating oil was not added until the reaction had been completed, theprecipitated sodium acetate ltered and a portion of the butyl alcoholstripped from the ltrate. The procedure was otherwise the same as forExample 3, except that reuxing conditions during the reaction weremaintained for 30 hours for a portion of the sample fand for 48 hoursfor the balance of the sample.

total yield of 2830 grams of a. 50% concen..

trate was obtained. The.- tests on the sample which had been refluxedfor hours are typical, with an ash content of'4.21 basedon a theoreticalof' 4.45%, and. a zinc content of" 2.63 based on a theoretical of 3.58%.The material yas soluble to the extent ofdissolving at least 1% of thezinc alkyl phenolate in the residual airplane. engine oil of 120 grade,and had excel.- lent' stability as evidenced by the solution remainingclear for two months storage at 120 F. and'also at room temperature. Theproduct was employed in engine testing with greatly improved results incomparison to the tests on the products of the previous examples, aspointed out'hereinbelow.

EXAMPLE 6 Based on the foregoing results including the engine tests, aVso-called standard procedure was developed in accordance with thefollowingv example. The materials employed were:

Czsfalkylphenoln" 1 844 grams (2 niols) Sodium metal 46 grams (2 inols)Zinc acetate CP fuse 200 grams (1 mo1+ 17 grains) Butyl alcohol (dry)2,500 mls. Naphthene basel distillate lubricating oil 900 grams rhebutyl alcohol was dried by distillation before use. The sodium metal wasmaintained and out under toluene. All open condenser-s and iiasks wereprotected from moisture in the atmosphere by the use of drying. tubes.All stripping was carried out by the use of dry air.

The alkyl phenol, zincV acetate and a portion ofthe dry'butyl alcoholwere charged to the reactor and the reactants heated to' 50 C. Thesodium' was reacted in aV separate 'vessel with remaining dry butylalcohol. The sodium butylate solution was then added dropwise to theother reactantsla-t' 50 C. Following the'raddition of the' sodiumbutylate.v solution,l the temperature was gradually increased to" butylalcohol reflux and this was maintained for 2`4'hours. The reaction mixwas*I then. filtered and the naphthene.

base: distillate-lubricating oil, whicliwas sufiicient to make a 50%concentrate, was added to. the filtrate: The butylY alcohol was thenstripped with the;` aid"V of: dry. air. After stripping, the product,was dissolved in about an equal volume of dry pentane, reiiltered andthe pentane removedby; stripping with dry air.

Ayieldgwasobtained of 1038 grams of concentrate-analyzing 2.96%. ashDwith a theoretical of 4.46%, and 1.95% zinc with a` theoretical of3.58%. While the products prepared by this standard procedure generallyhave low ash and zinc contents as illustratedby` theioregoing, thisappears to be characteristic of entirely satisfactory zinc alkylphenolate preparations for'pure poses ofthe presentinvention. Thus this'product was satisfactorily solublev to theextentf of 1%, of the zincalkyl phenolate in the. residual airplane Lle() and also to prevent theformation of objectionl able combustion chamber, deposits. Final proofof' the quality of the zinc alkyl phenolate preparation was thereforesecured by the'actual engine testing of the preparation in conjunctionw-ith a magnesium alkyl phenolate of known satisfactory quality in anairplane engine oil, as set forth in the following table. In that table,ZP designates zinc' alkyl phenolate, MP designates magnesium alkylphenolate, and the numeral following the designation for these metallicphenolates signifies theI average carbon atom content of the alkyl sidechain on each benzene nucleus of the salt.

The CFR High Speed Engine Testof the table is recognized as a reliablescreening test for determining the ability of a crank case lubricatingoil to reduceengine deposits under severe operating conditions.Thistestis carried out with a standard CFR single cylinder engineoperating under the following conditions:

Compression ratio 6.5 1

O il in temperature Oil out temperature Fuel 100 octane (minimum) avia#tion type containing: 4 Yccs; TEL/gal.

Duration of run 50 hours` In this test, electrical measurements aretaken of the piston skirt deposit with respect to the extent orpercentage of surface area' of the piston skirt which is covered. by thelacquer. deposit at the termination of each run, together with theaverage thickness' of' the deposit expressed in inches 104. Goodreproducibility from .run to run isv obtained in the piston skirtlacquer de posit; and the test is therefore recognized as an accurateindication of the engine cleanliness of the oil composition under test.

Thefollowing results were obtained in this CFRHigh Speed: Engine Test,utilizing the zinc alkyl phenolate preparations described above inconjunctiony withv magnesium alkyl phenolate of known good quality inthe proportions indicated, ina residual airplaneengineoil having an SUSviscosity'at 210 F. of about 120 and designated AEO 120.`

Table CFR High Speed Engine Test Piston Zn Alkyl Phenolate Pro- PercentSecondary Percent Sklrt Deposit cedure y C one. Additive Conc.l

Covered, Thickness, K Percent infXlO4 1. Example l, ZPV-24`.. 0. 5M12-24 1. 0 32 0.17 2. Example 2, ZP-23-. 0.5 M13-23 1. 0 37 0.' 53' 32Example 3, ZP-21.. (1.'5 MP23 1.0 39 0.19 4.. Example 4, ZP-23 v 0. 5MP23 1. 0 21 0. 08 5. Example 5, ZP-23 0. 5 M12-23 1. 0 0 0. 00 6;Example 5, ZP-23; 1 0. 5 MIT-23 1. 0 8 0101 7. Example 6, ZIP-23.. 0.5MIJ-23 1. 0 0 0. 00 8. Standard ZP-21. 0. 5l MP-21 1.0 0 0.00 9;Standard ZP-Zl 0. 5 MP-2l l. 0 0 0. 00 10. Base oil alone, AEO 120. 2.0

Run of the foregoing table shows that the base oil alone fails tomaintain engine cleann liness, since the piston was 80% covered with acomparatively thick lacquer deposit. On the other hand, a Zinc alkylphenolate of the proper quality in conjunction with magnesium alkylphenolate of the proper quality, when employed in proportions of theorder shown in the table, will maintain excellent engine cleanliness,and give in this engine test a piston substantially without measurablelacquer deposit on the skirt.

Runs 1-4 inclusive of the table employed the zinc alkyl phenolatepreparations of the foregoing Examples 1-4 respectively. While most ofthese products had ash and Zinc contents fairly close to theoretical,and some had fair solubility and storage stability, nevertheless theengine tests showed these products to be unsatisfactory as a detergentadditive for the crankcase lubricating oil, since they failed tomaintain the desired engine cleanliness. In the light of presentknowledge, it appears evident that these earlier preparations failedbecause the required anhydrous conditions of reaction were notmaintained, the proper long reaction time was not employed, thedistillate mineral lubricating oil was added prior to the reaction, andother procedural steps as enumerated above were not followed.

Runs 5 and 6 employed the two samples of the zinc alkyl phenolateproduced in accordance with Example 5 above, wherein the standardprocedure was employed except that the final reltration in the lpresenceof added light hydrocarbon solvent v was not used. While the results ofthese runs showed 4very substantial improvement, Run of the table gave ameasurable lacquer deposit in vthe engine test; l

Run 7 of the table employed the product kmade by the standard procedureof Example 6. Run 8 of the table employed a zinc alkyl phenolatepreparation of different molecular weight which was also made by thestandard procedure of Example 6. Run 9 of the table employed a zincalkyl phenolate preparation made by the standard procedure, using inthis case zinc chloride as the re actant inplace of the Zinc acetate ofExample 6. As shown, these products were uniformly of excellent qualityas detergent additives for the crank case lubricating oil. `In additionto overcoming diiculties of filtration and puriiication of the productas encountered with the procedure of the prior art, the synthesis methodof the present invention has been found to uniformly produce zinc alkylphenolateproducts fromthese high molecular weight C-C20 alkyl phenolshaving the required solubility and stability in the residual airplaneengine oil, and also theV desired high quality as a detergent additivein maintaining excellent engine cleanliness.

Obviously many modications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof and, therefore, only such limitations should beimposed as are indicated in the appended claims.

We claim:

1. In the manufacture oi a zinc salt of an alkyl substituted hydroxyaromatic hydrocarbon consisting of carbon, hydrogen and oxygen, whereinthe alkyl substituent on the ring contains from 15 to 30 carbon atoms,the improvement to obtain a zinc salt of at least 1% by weightsolubility in a residual mineral lubricating oil of the airplane engineoil type and which has eiective engine cleanliness properties, whichcomprises mixing under substantially anhydrous conditions and in theproportion of substantially one molar amount of an alkyl substitutedhydroxy aromatic hydrocarbon consisting of carbon, hydrogen and oxygen,one molar amount of an alkali metal alcoholate of an aliphatic alcoholcontaining 4 to 5 carbon atoms in the molecule and boiling above theboiling point of water, said alkali metal alcoholate being in solutionin an excess of the said anhydrous alcohol, and slightly more thanonehalf molar amount of a soluble zinc salt whose acidic portion formsan alkali metal salt which is ins-oluble in the said anhydrous alcohol,reacting the said mixture under refluxing conditions of the said C4 toCs aliphatic alcohol for a period of time in excess of 20 hours toproduce an anhydrous alcohol solution of the Zinc salt of the alkylsubstituted hydroxy aromatic hydrocarbon in which the alkali metal saltis precipitated, ltering to remove the precipitated alkali metal salt,adding to the ltrate a dry mineral lubricating oil, and stripping toremove the alcohol under anhydrous conditions to recover an anhydrousmineral lubricating oil concentrate of the said zinc salt having theaforementioned properties.

2. The method according to claim l, wherein the alkyl substitutedhydroxy aromatic hydrocar bon and the zinc salt are premixed, and theanhydrous vC4 to Cs aliphatic alcohol solution of the alkali metalalcoholate is slowly added to the premixture at a lower temperature ofthe order of 30-70 C. and the resulting mixture is then raised to thealcohol reiiuxing temperature.

3. The method according to claim 2, wherein the said stripped minerallubricating oil concentrate of the Zinc salt is mixed with a dry lighthydrocarbon solvent, the resulting mixture is reiltered, and the lighthydrocarbon solvent is then stripped from the iiltered concentrate underanhydrous conditions.

4. The method according to claim 1, wherein the alkyl substitutedhydroxy aromatic hydrocarbon is a C15 to Cso alkyl phenol, and theanhydrous C4 to Cs alcohol is a butyl alcohol.

JOHN W. HU'rcHEsoN. EDWIN C. KNOWLES.

References Cited in the file of this patent UNITED STATES PATENTS cNumber Name Date 2,197,833 Reiff Apr.'23, 1940 2,399,877 McNab et a1 May7, 1946 2,610,982 Hutcheson Sept. 16, 1952

1. IN THE MANUFACTURE OF A ZINC SALT OF AN ALKYL SUBSTITUTED HYDROXYAROMATIC HYDROCARBON CONSISTING OF CARBON, HYDROGEN AND OXYGEN, WHEREINTHE ALKYL SUBSTITUENT ON THE RING CONTAINS FROM 15 TO 30 CARBON ATOMS,THE IMPROVEMENT TO OBTAIN A ZINC SALT OF AT LEAST 1% BY WEIGHTSOLUBILITY IN A RESIDUAL MINERAL LUBRICATING OIL OF THE AIRPLANE ENGINEOIL TYPE AND WHICH HAS EFFECTIVE ENGINE CLEANLINESS PROPERTIES, WHICHCOMPRISES MIXING UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS AND IN THEPROPORTION OF SUBSTANTIALLY ONE MOLAR AMOUNT OF AN ALKYL SUBSTITUTEDHYDROXY AROMATIC HYDROARBON CONSISTING OF CARBON, HYDROGEN AND OXYGEN,ONE MOLAR AMOUNT OF AN ALKALI METAL ALCOHOLATE OF AN ALIPHATIC ALCOHOLCONTAINING 4 TO 6 CARBON ATOMS IN THE MOLECULE AND BOILING ABOVE THEBOILING POINT OF WATER, SAID ALKALI METAL ALCOHOLTE BEING IN SOLUTION INAN EXCESS OF THE SAID ANHYDROUS ALCOHOL, AND SLIGHTLY MORE THAN ONEHALFMOLAR AMOUNT OF A SOLUBLE ZINC SALT WHOSE ACIDIC PORTION FORMS AN ALKALIMETAL SALT WHICH IS INSOLUBLE IN THE SAID ANHYDROUS ALCOHOL, REACTINGTHE SAID MIXTURE UNDER REFLUXING CONDITIONS OF THE SAID C4 TO C6ALIPHATIC ALCOHOL FOR A PERIOD OF TIME IN EXCESS OF 20 HOURS TO PRODUCEAN ANHYDROUS ALCOHOL SLUTION OF THE ZINC SALT OF THE ALKYL SUBSTITUTEDHYDROXY AROMATIC HYDROCARBON IN WHICH THE ALKALI METAL SALT ISPRECIPITATED, FILTERING TO REMOVE THE PRECIPITATED ALKALI METAL SALT,ADDING TO THE FILTRATE A DRY MINERAL LUBRICATING OIL, AND STRIPPING TOREMOVE THE ALCOHOL UNDER ANHYDROUS CONDITIONS TO RECOVER AN ANHYDROUSMINERAL LUBRICATING OIL CONCENTRATE OF THE SAID ZINC SALT HAVING THEAFOREMENTIONED PROPERTIES.